An inkjet recording head comprises a nozzle that discharges droplets of ink, an ink pressure chamber communicating with the nozzle, and an actuator that applies pressure to the ink in the ink pressure chamber. This head drives the actuator to apply pressure to the ink in the ink pressure chamber and discharge droplets of ink from the nozzle.
A piezoelectric type actuator, for example, is known as a type of actuator that discharges droplets of ink by deforming and displacing the wall (vibration plate) of an ink pressure chamber using a piezoelectric element. An advantage of the piezoelectric type actuator is freedom from constraints on the type of ink to be used, since the piezoelectric element does not directly contact the ink, and the heat generated by the piezoelectric element may be ignored. Thus, a piezoelectric MEMS type inkjet recording head developed by applying the semiconductor processing technology to such a piezoelectric type actuator is drawing attention.
When pressure is applied to ink in an ink pressure chamber and droplets of the ink are discharged from a nozzle, the pressure of the ink in the ink pressure chamber needs to be maintained in order to obtain a sufficient discharge pressure. Therefore, a narrow portion (an orifice) is typically provided between an ink pressure chamber and an ink supply path.
Meanwhile, air bubbles formed in the ink pressure chamber during an ink discharge operation absorb the pressure for discharging ink droplets, resulting in poor discharge. Therefore, a head designed to remove air bubbles by circulating ink in an ink pressure chamber is known.
However, an orifice provided on the ink supply path prevents the ink from smoothly flowing, resulting in insufficient removal of air bubbles.
Under the circumstances, there is a demand for an inkjet recording head that favorably discharges ink droplets at a sufficient discharge pressure.